@Zooldrool
This article is a Bulgarian perspective, so, of course, there are bound to be significant differences between the main cities (Sofia, Plovdiv, Varna, Burgas) and everywhere else. But from a more international perspective (e.g. for a Brit moving from the UK) the economic/cost differences would be much more marginal. The property cost difference might still be significant enough to appeal in less populated/popular regions like the south-east (Greece/Turkey border) and north-west (Romania/Serbia border).
In my view, some folks do research countries and areas/cities, but most kinda go with the flow (i.e. they go where their job is, or where they find a house - or person, perhaps - that appeals). With the price of property being so high, and the internet being so easy/visible, I doubt I'm the only one who's found something cheap-and-cheerful online and then moved there! Once you've made that initial commitment/investment, the place has to be "good enough", rather than the best option possible.
Veliko Tarnovo, for example, has been a region popular with expats for many years. It has a lot to recommend it. Ditto for the Black Sea coast. And, of course, a country's capital city (Sofia in this case) is always a safe bet (but usually the most expensive one). If we'd gone there first, we'd still be there, I'm sure. They're all perfectly fine (indeed, the Black Sea coast is rather nice, and I would have gone there if I was not grossed out by swimming in the Black Sea itself, as I'm a spoiled brat after years of daily swims in the Med).
Our zones are mostly accidental. Long ago, I looked around for cheap ski resorts (I'm a former ski instructor) and found Bansko... and a very cheap 1 bed flat in the centre. I then visited to see what I'd purchased, and loved Bansko (still do), but hated Bulgarian Standard (still do, what a hassle!). 15 years later, it's still sitting there unfinished, and we have a finished holiday studio nearby. Bansko is the country's top ski/mountain resort, and it's a very charming little town. It's a bit too dinky for my taste (especially as I have a place with the comforts/conveniences of a big city), but I'd say it's totally livable year-round.
Later, when I was looking around for the best/easiest country for a Brexit-beating EU residence permit, it seemed silly not to include Bulgaria as I already owned a property there... and my immigration attorney is in Plovdiv. Never heard of the place, but liked it (a lot) in the 3 days I spent here to get my card, So we purchased a city pied-a-terre, and we're still hanging out 8 years later. It's a tip-top city, and a great - if lucky - choice that I'd enthusiastically recommend to anyone. Finally, our village house is out in the mountains (Balkan) next to Shipka and Kazanlak. Purchased based on the agent's pretty pictures and the Google Street View of the mountains next to the village. Great house, great village, great region, great mountains/outdoor life - again, very lucky, given the limited research (and buying online without viewing). I love the place and could happily live there full-time.
That I can stumble on 3 regions and love them all seems to me to be extremely unlikely if the rest of the country is horrible! My guess is that most of the country is very acceptable, as long as you find yourself a property that you like, and make sure you're within a reasonable distance of civilization (and not next door to a Bobov Dol coalmine, a Kozloduy nuclear reactor, or a Romany enclave). In our case, our village house is 10km from Kazanlak and Kaufland/Lidl. 10-ish km from a 40k+ town seems pretty much ideal to me, and there are plenty of nice Bulgarian towns this size and up. Some might even be OK with smaller (5k-20k) and further away (15km-25km), in order to save more on their house price.
